1. Technical Field
The present invention relates to a printer that has a suction unit such as a vacuum platen that pulls the recording paper to the platen surface while the paper is conveyed, and relates more particularly to a printer having a ventilation path that rectifies the exhaust current of a centrifugal fan that produces air flow through the suction unit.
2. Related Art
Inkjet printers that have a vacuum platen to prevent the roll paper or other recording medium conveyed over the platen from lifting up and interfering with the nozzle surface of the inkjet print head are known from the literature. A vacuum platen has a suction unit with numerous air holes formed in the surface, and the suction unit is connected to the intake opening of a vacuum fan through an air path such as an air duct. When the vacuum fan operates, the suction unit produces an air flow that pulls the recording medium conveyed over the vacuum platen to the platen surface. A centrifugal fan such as a sirocco fan is commonly used as the vacuum fan.
Japanese Unexamined Patent Appl. Pub. JP-A-2002-147396 teaches an inkjet printer that has a vacuum platen. More particularly, JP-A-2002-147396 teaches technology for reducing turbulence in the flow of air pulled into the intake opening of the centrifugal fan so that air can be pulled in efficiently by the vacuum fan.
If an exhaust path is formed on the downstream side of the exhaust opening of the centrifugal fan and the exhaust flow produced by air discharge is rectified, the exhaust can flow smoothly and the centrifugal fan can pull air in efficiently.
However, the exhaust from the centrifugal fan tends to continue flowing along the rotating path of the fan blades even after the exhaust is discharged from the exhaust opening due to inertia. As a result, if the exhaust path is not suitably disposed, the exhaust flow becomes turbulent inside the exhaust path, inhibiting a smooth discharge, inviting loss of exhaust flow, and reducing fan performance. Another problem is that the turbulence produced in the exhaust path hits the inside walls of the exhaust path and produces noise.